http://dspace.nbuv.gov.ua:80/handle/123456789/132730 2026-04-20T23:46:54Z http://dspace.nbuv.gov.ua:80/handle/123456789/136757 Investigation of the effect of water content and degree of compaction on the shear strength of clay soil material Zhang Huzhu; Liu Hanbing; Wang Jing; Dong Weizhi The effect of water on compacted clay material with the use of triaxial compression was studied, and models for predicting shear strength parameters were also developed. The results show that cohesion decreases exponentially with increasing water content and exponentially increases with increasing degree of compaction. The angle of internal friction decreases in a convex quadratic parabolic law with increasing water content and increases with a concave quadratic parabolic law with an increase in the degree of compaction; Cohesion and internal friction angle are two-dimensional quadratic functions of water content and degree of compaction and have relatively large values of the shear strength parameter. 2017-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/136754 Study of influencing factors on the peak dissipation energy at physical simulation similar material of coal-rock solid-gas coupling Zhao Peng-xiang; He Bin-lei; Xiao Peng; Yang Erhao; Gao Jin-biao Based on the study of the test specimens made with the new solid-gas coupling similar material, the variation rule of energy characteristics during the compression and rupture of rocks and the criterion to judge rock damage were obtained. The results show that during the process of uniaxial fracturing, the peak dissipation energy of the test specimen has a logarithmic relationship with the bone-glue ratio, while it has a positively correlated exponential relationship with the mass ratio of gas-barrier cementing agent. It was shown that the sensitivity of peak dissipation energy toward the mass ratio of gas-barrier cementing agent is more obvious. The research results have provided the theoretical basis for the quantified appraisal of the fracture evolution region. 2017-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/136753 Control of chromium dopant content in optical ceramics Cr:YAG Gayduk, O.V. Spectrophotometric determination of chromium in the presence of predominating yttrium and aluminum quantities was investigated by the method based on the reaction Cr(VI) with diphenylcarbazide. The optimum conditions of Cr(III) oxidation by potassium permanganate were established. A spectrophotometric technique for determination of 0.005-0.3 % of chromium in Cr-doped yttrium aluminum garnet ceramics was developed. The determination error is 1-5 %. 2017-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/136752 Study of Mn²⁺ and MnO₄⁻ products interaction in alkaline solution Sofronov, D.S.; Odnovolova, A.M.; Gudzenko, L.V.; Desenko, S.M.; Mateychenko, P.V.; Rudenko, L.V.; Lebedynskiy, A.M. Interaction of Mn²⁺ ions with MnO₄⁻ in alkaline medium is considered. The main component of this interaction is manganese oxyhydroxide MnO(OH) and not manganese dioxide, that is revealed by means of X-ray diffraction analysis, IR-spectrometry and chemical analysis. It is demonstrated that decomposition of MnO(OH) occurs in the wide temperature range (60-550 °C), that results in mixture of Mn₂O₃ and MnO₂ oxides formation. 2017-01-01T00:00:00Z